[REPORT] 2.6.21 vs. 2.6.21-sd046 vs. 2.6.21-CFSv7

[REPORT] 2.6.21 vs. 2.6.21-sd046 vs. 2.6.21-CFSv7

Post by Bill David » Wed, 02 May 2007 04:40:09


System: Intel 6600 Core2duo, 2GB RAM, X nice 0 for all tests, display
using i945G framebuffer

Test: playing a 'toon with mplayer while kernel build -j20 running.

Tuning: not yet, all scheduler parameters were default

Result: base 2.6.21 showed some pauses and after the pause the sound got
louder for a short time (<500ms). With sd-0.46 the playback had many
glitches and finally just stopped with the display looping on a small
number of frames and no sound. The skips were repeatable, the hang was
only two of five runs, I didn't let them go until the make finished
(todo list) but killed the mplayer after 10-15 sec. No glitches observed
with cfsv7, I thought I saw one but repeating with granularity set to
500000 and then with no make running convinced me that it's just a
crappy piece of animation at that point.

I ran glxgears, again sd-0.46 had frequent pauses and uneven fps
reported. Stock 2.6.21 had a visible pause when the frame rate was
output, otherwise minimal pauses. CFSv7 appeared smooth at about 250 fps.

All tests gave acceptable typing echo, it seems that X is getting enough
time at that load to echo without major issues.

I will be doing tests with server load later this week, have to add disk
for the database.

Hope this initial report is useful, I may be able to update ctxbench
later today and try that.

--
Bill Davidsen < XXXX@XXXXX.COM >
"We have more to fear from the bungling of the incompetent than from
the machinations of the wicked." - from Slashdot

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[REPORT] 2.6.21 vs. 2.6.21-sd046 vs. 2.6.21-CFSv7

Post by Bill David » Wed, 02 May 2007 05:00:09


Followup: I reran with sd-0.46, setting rr_interval to 40, and then 5
(default was 16). Neither appeared to give a useful video playback. I
did try setting the make to nice 10, and that made the playback
perfectly smooth, as well as response to skip forward and volume change
happening when the key was pressed instead of eventually.

I also tried raising the nice of X to -10, that made things better on
display, but I winder if it will let X run ahead of the nice-0 raid threads.

Is this my hardware or is there a really odd behavior here? The sd seems
to be too fair to cope well with this realistic load, and expecting
users to nice things is probably morally correct but unrealistic.
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[REPORT] 2.6.21 vs. 2.6.21-sd046 vs. 2.6.21-CFSv7

Post by Bill Hue » Wed, 02 May 2007 05:20:11


People have been reporting very good performance with regards to OpenGL
applications under SD. What is your video driver ? NVidia proprietary ?

OpenGL, X and direct frame buffer access (mplayer and friends) tend not
to interact each other which can result in very different scheduling
characteristics between them.

[please CC the relevant people for their own benefit]

bill

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[REPORT] 2.6.21 vs. 2.6.21-sd046 vs. 2.6.21-CFSv7

Post by Con Koliva » Wed, 02 May 2007 08:00:07


Bill thanks for testing.

Umm I don't think make -j20 is a realistic load on 2 cores. Not only does it
raise your load to 20 but your I/O bandwidth will even be struggling. If
video playback was to be smooth at that size a load it would suggest some
serious unfairness. I'm not just pushing the fairness barrow here; I mean it
would need to be really really unfair unless your combined X and video
playback cpu combined added up to less than 1/20th of your total cpu power
(which is possible but I kinda doubt it). Do you really use make -j20 to
build regularly?


I did notice on your followup email that nice +10 of the 20 makes fixed the
playback which sounds pretty good.


I assume you mean glxgears when you're running make -j20 again here.


That's nice; shows stability under load.


Great.


Also good.

--
-ck
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[REPORT] 2.6.21 vs. 2.6.21-sd046 vs. 2.6.21-CFSv7

Post by Bill David » Fri, 04 May 2007 00:20:07


My original post I was following gave my config, built-in graphics using
945G framebuffer. This is a server, I'm not a gamer. The only fancy
graphics I have are on a system with no on board video at all, I picked
up a moderately high-end Radeon card to drop in. And to give you an idea
of what a gamer I am, that uses the vesafb driver ;-)

--
bill davidsen < XXXX@XXXXX.COM >
CTO TMR Associates, Inc
Doing interesting things with small computers since 1979

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[REPORT] 2.6.21 vs. 2.6.21-sd046 vs. 2.6.21-CFSv7

Post by Bill David » Fri, 04 May 2007 00:20:08


Yes, this is a compile and file server, I frequently build a raft of
kernels when a security patch comes out. There doesn't seem to be an i/o
issue, with 2GB RAM and RAID5 over a SATA array I have enough, but
honestly the disk activity is minimal, even with a single drive.
Yes, I can get around the load doing that.
Of course. ;-)

--
bill davidsen < XXXX@XXXXX.COM >
CTO TMR Associates, Inc
Doing interesting things with small computers since 1979

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